University of Plymouth PEARL https://pearl.plymouth.ac.uk 04 University of Plymouth Research Theses 01 Research Theses Main Collection 1994 TEMPERATURE AND PERIOD DEPENDENCE IN THE POST-DIAPAUSE DEVELOPMENT OF THE CABBAGE ROOT FLY, DELIA RADICUM ROBERTS, LORNE GEORGE http://hdl.handle.net/10026.1/2523 University of Plymouth All content in PEARL is protected by copyright law. Author manuscripts are made available in accordance with publisher policies. Please cite only the published version using the details provided on the item record or document. In the absence of an open licence (e.g. Creative Commons), permissions for further reuse of content should be sought from the publisher or author. TE:MPERATURE AND PERIOD DEPENDENCE IN THE POST-DIAPAUSE DEVELOPMENT OF THE CABBAGE ROOT FLY, DELIA RADICUM by LORNE GEORGE ROBERTS A thesis submitted to the University of Plymouth in partial fulfilment for the degree of DOCI'OR OF PHILOSOPHY Department of Biological Sciences Faculty of Science In collaboration with ADAS, Starcross April1994 !f3 10'1:" . .. ' ' ~1-\V' .~ ~ I " ] ,J 5 ' . ' """"""""'"'~ ... UN\\JE.RS\1'\' 0~ Pl..'lMOUiH L\SR~\'-\'1 SEt:\V\CeS . ' \tem 0ro 224950 I NO· t CIQSS -r 5~5·1os14gRo-s No. con\\. 1--'1030604-'7 z No. ..... - ..... " -··-- I REF~RENCE ONLY 3 AUTHOR'S DECLARATION At no time during the registration for the degree of Doctor of Philosophy has the author been registered for any other University award. This study was financed with the aid of a grant from the S_cience and Engineering Research Council and carried out in collaboration with ADAS, Starcross. A programme of advanced study was undertaken which included a third year course in Ecology, main-frame computer instruction, consultation with staff of the collaborative institute, attendence and presentation of work at relevant coferences and seminars. 4 ACKNOWLEDGEMENTS It is with pleasure that I extend my sincere thanks to a number of very patient, hardworking and helpful people who have supported me over the years:- To my supervisor, Professor C. Hawkes, for the opportunity to study at PhD level. During my research at Plymouth University he has remained a constant source of constructive criticism, reasoned interpretation, efficient supervision and encouragement. To Mrs. A. Torr and Mr. P. Smithers for their hardworking yet cheerful technical assistance and friendship. They are a credit to their profession. To all the technical staff within Plymouth University who assisted me with laboratory, computer and field work. To Mr. Tucker, Mr. Rew and Mr. Pike for the use of their land and crops during the field studies. I hope any inconvenience to them was minimal. To RAF Mountbatten and Bracknell Meteorological Offices for their data. To Mr. G. Regan for his help with computer programming and the loan of his PC and printer. 5 CONTENTS PAGE COPYRIGHT 1 TITLE PAGE AUTHOR'S DECLARATION 3 ACKNOWLEDGEMENTS 4 CONTENTS s List of figures 10 List of tables 15 CHAPfERONE GENERAL INTRODUCTION 17 1:1 Delia radicum - The Cabbage Root Fly 17 I: I: I Crop Losses and Damage Asessment I7 I: I:2 Life Cycle 20 I: I:3 Behaviour and Ecology 21 1: I:4 Control 26 1:2 Diapause 32 I:2: I The Diapause Syndrome 32 I:2:2 Stages Entering Diapause 37 I:2:3 Stages· Sensitive to Diapause Induction Stimuli 39 I:2:4 Diapause Development 4I I:2:5 Post-diapause Transitional Periods 46 1:3 Diapause in Delia radicum 49 I :3:1 Diapause Induction 49 I:3:2 Diapause Development 52 I:3:3 Post-Diapause Development 54 1:4 Late Emergence and Year-Delayed Emergence 60 6 PAGE 1:4: 1 Evidence for Late Emergence in Delia radicum 61 1:4:2 Ecological and Agricultural Implications 66 1:4:3 Evidence for Year-Delayed Emergence in Delia radicum 69 1:4:4 Ecological and Agricultural Implications 70 1:5 The Problem . 72 1:6 Aims and Objectives 74 CHAPfER TWO FIELD INVESTIGATIONS INTO LATE AND YEAR-DELAYED EMERGENCE IN D. RADICUM 75 2:1 Trapping Methods 77 2: 1: 1 Emergence Traps 79 2:1:2 Pilot Experiments 79 2:2 Field Investigations 94 2:2: 1 1988 Sites and Distribution of Traps 94 2:2:2 1989 Sites and Distribution of Traps 105 2:2:3 1990 Sites and Distribution of Traps 114 2:3 Results or Field Investigations 117 2:4 Discussion or Field Investigations 126 CHAPfER THREE INVESTIGATIONS INTO TEMPERATURE DEPENDENCE IN POST~DIAPAUSE DEVELOPMENT USING COMPUTER SIMULATION MODELS 137 3:1 Introduction 137 3:2 Computer Model 1 - 'Secondary Diapause Hypothesis' 141 3:2:1 Assumptions 144 3:2:2 Results and Discussion 146 7 PAGE 3:3 Computer Model 2 - 'Warm-up Hypothesis' 150 3:3:1 Assumptions 150 3:3:2 Results and Discussion 152 3:4 Computer Model 3 - 'Potential and Actual Rate Hypothesis' 159 3:4:1 Assumptions 159 3:4:2 Results and Discussion 162 3:4:3 Experiment Testing Model 3 165 CHAPrER FOUR LABORATORY EMERGENCE STUDIES 173 4:1 Cultures 173 4:2 Delayed Emergence from Non-diapausing Pupae 175 4:2:1 Introduction 175 4:2:2 Further Investigations 175 4:2:3 Selection and Rearing of Late Emerging Non-diapausing 180 Flies 4:2:4 Results 180 4:2:5 Discussion 205 4:3 Emergence from Year Delayed Cultures 209 4:3:1 Method 209 4:3:2 Results 209 4:3:3 Discussion 210 4:4 Post-diapause Development Emergence Studies 212 4:4:1 Methods 212 4:4:2 Results 224 4:4:3 Discussion 258 4:5 Selection and Rearing of Early and Late Emerging 285 Diapausing Flies 4:5:1 Methods 285 4:5:2 Results 286 8 PAGE 4:5:3 Discussion 291 CHAPTER FIVE . FURTHER INVESTIGATIONS INTO TEMPERATURE DEPENDENCE IN POST-DIAPAUSE DEVEWPMENT BY COMPUTER SIMULATION 297 5:1 Evaluation of Previous Hypothesis in Light of Laboratory Emergence Studies 297 5:2 Model A - Intermediate Diapause/Potential and Actual 299 Rate Hypothesis 5:2:1 Assumptions 299 5:2:2 Method - version 1 303 5:2:3 Results and Discussion 304 5:2:4 Method - version 2 304 5:2:5 Results and Discussion 311 5:3 Model B - Alternative Development Hypothesis 316 5:3:1 Additional Assumptions 316 5:3:2 Method 317 5:3:3 Results 320 5:3:4 Discussion 321 5:4 Model C - Intermediate Diapause Hypothesis for Late Emergers 325 5:4:1 Method - version 1 325 5:4:2 Results and Discussion 326 5:4:3 Method - version 2 333 5:4:4 Results 333 5:5 Discussion of Computer Simulation Models 338 CHAPTER SIX GENERAL DISCUSSION 340 6:1 General Discussion 340 9 PAGE 6:2 Future Research 347 APPENDIX REFERENCFS 10 LIST OF FIGURES FIGURE TITLE PAGE NUMBER 1 Schematic representation of the course of diapause in the 51 cabbage root fly (Collier & Finch, 1983a). 2 Brindle's 'two phase response':- Metabolic rate of DCE in 58 experiment 1 (Brindle, 1986). 3 Emergence from parental and F1 cultures in selection 64 experiment (Finch & Collier, 1983). 4 Flower pot trap and capture tube. 81 5 Gutter trap. 83 6 Combined pilot study data comparing fly emergence from 90 flower pot and gutter traps. 7 Stokenham site. 96 8 Bigbury sites. 98 9 Bigbury site- crop positions for 1987. 100 10 Bigbury site - crop positions for 1988. 102 lla Photograph of gutter traps laid amongst potato crop at 104 Stokenham site, 1988. llb Photograph of gutter traps laid amongst potato crop at 104 Bigbury site a), 1988. lie Photograph of gutter traps laid amongst barley crop at 107 Bigbury site b), 1988. lld Photograph of flower pot traps laid amongst wheat crop 107 at Suffolk site, 1989. 12 Bigbury site -crop positions for 1989. 110 13 Suffolk site. 112 11 F1GURE TITLE PAGE NUMBER 14 Bigbury site - crop positions for 1990. 116 15 Cabbage root fly emergence distribution from all three 121 sites for 1989. 16 Number of flies caught in yellow water traps within an 136 emergence cage at Halsall, Lancashire (Finch & Collier, 1983). 17 Schematic representation of the 'secondary diapause 143 hypothesis'. 18 Rates of development in 'secondary diapause hypothesis' 149 using consistent rises in temperature. 19 Rates of development in 'warm-up hypothesis' using 154 consistent rises in temperature. 20 Theoretical rates of development using Brindle's 156 temperature regimes for the 'warm-up hypothesis'. 21 Theoretical rates of development showing 'step 158 response' in 'warm-up hypothesis'. 22 Schematic representation of the 'actual and potential rate 161 hypothesis'. 23 Rates of development in 'actual and potential rate 164 hypothesis' using consistent rises in temperature. 24 Theoretical rates of development using Brindle's 167 temperature regimes for the 'actual and potential rate hypothesis'. 25 Theoretical rates of development for experimental 171 regimes using 'actual and potential rate hypothesis'. 26 Cabbage root fly emergence distributions from three 179 cultures - set 1. 27 Maximum times to 50, 75 and 90 percent emergence 185 from non-diapausing culture pupae - set 1. 12 FIGURE TITLE PAGE NUMBER 28 Cabbage root fly emergence distributions from three 189 cultures - set 2. 29 Maximum times to 50, 75 and 90 percent emergence 191 from non-diapausing culture pupae- set 2. 30 Cabbage root fly emergence distributions for four 196 cultures - set 3. 31 Maximum times to 50, 75 and 90 percent emergence 198 from non-diapausing culture pupae- set 3. 32 Comparison of cabbage root fly emergence distributions 200 from the Seale Hayne culture over long periods of time. 33 Comparison of cabbage root fly emergence distributions 202 from the late emergers culture over long periods of time. 34 Comparison of cabbage root fly emergence distributions 204 from the Plymouth and Wellesboume culture over long periods of time.